Crimped tube containers are widely known and generally consist of a main tubular body member for holding contents having a restricting neck to a smaller diameter throat leading to an open dispensing first end at one end of the main body member and a larger open second end at the opposite end of the main body. The main body is generally tubular, but may be other shapes, and the second end is normally used for filling the tubes with product. Thereafter the tube's filling end is generally closed by crimping. Where the body member is made of plastic the crimping may include heat sealing or other known plastic bonding processes to close the open filling end.
However, a class of such containers is made of soft metal such as aluminum which is particularly desirable for certain products, including those types of products which benefit from protection against moisture, air contact, UV exposure and the like.
As described in my previously published application 2004/0173558, the contents of which are herein incorporated by reference, such metal tubes are particularly applicable for use with adhesives such as cyanoacrylates. In such instances the mouth opening is generally closed off with a pierceable membrane formed in the throat of the tube, and the cyanoacrylate product is filled from the opposite open end. Such filling may be under controlled atmosphere conditions and may, in certain instances, be made in the presence of inert gasses.
Such soft metal tubes have been used for cyanoacrylate for many years and after filling are crimped closed in the normal manner, which usually includes both a folding and a mashing or crimping operation at the tube filling open end.
While such tubes are particularly useful for materials such as cyanoacrylates, which can then be dispensed in somewhat controlled quantities by piercing the membrane closure and then controllably squeezing the tube, due to the softness and the yieldability of the tube accurate dispense pressure is difficult to maintain, and more importantly, the tube tends to remain in its squeezed state and will not return to its original dimensions. This of course results in the inability to continue dispensing when the area being pressed becomes fully collapsed or when the material remaining in the tube is below the area in which pressure is applied and a compressed area of the tube blocks flow to the mouth.
This problem has long been recognized and in general such tubes are simply rolled up from the crimped end as the contents are dispensed so that the area above the rolled up end is generally retained in its original uncompressed state, or something close thereto, and can be squeezed to provide a somewhat controlled dispense. While such tubes have utility, their failure to be able to return to something approaching the pre-squeezed state so as to avoid the necessity of rolling up the bottom is a disadvantage, and their inability to suck back material from the neck or mouth area or from a dispensing nozzle affixed to a mouth presents an undesired limitation. This has led to the use of formed metal tubes for dispensing materials such as cyanoacrylates. As described in U.S. Pat. Nos. 5,799,829 and 6,726,060, the use of non-crushable metal tubes for dispensing cyanoacrylates can provide a sniff back or material drawback function when the squeezing pressure against the walls of the metal tube is released and the tube returns to its pre-squeezed condition while overcoming the disadvantages of crimped soft metal tubes but at a much greater expense.
As explained in my prior published application, somewhat the same advantage can be obtained in a crimp tube by providing an internal stiffener which may, for example, be formed of a material impervious to the crimp tube's contents but having a stiffness and resiliency sufficient to return the soft metal tube to its original shape when the external squeezing force is released. As shown in that application, this can be accomplished by internally positioned tubes having an outer diameter substantially equal to the normal inner diameter of the crimp tube when in its fully shaped condition.
In my earlier application I also described providing openings or cutouts through the inner tube to assist the inner tube in returning to its normal shape after squeezing.
While such inner tubes or stiffeners both provide for more accurate control of dispensing in that they provide a resistance to squeezing of the tube greater than would be provided by the soft metal of the tube itself, and also can provide for a sniff back into the main body of material dispensed into an applicator tip or the like, certain disadvantages have been identified, which, in part, have led to such internal tube stiffened soft metal crimp tubes not being accepted in the industry. Among the disadvantages are the fact that the internal stiffening tube, having a diameter the same as the normal maximum inner diameter of the metal tube, can chafe against the metal tube interior, particularly at the ends of the stiffener and can provide pressure points that may lead to a failure of the integrity of the soft metal crimp tube. Additionally, the contents of the tube will find its way into the area surrounding the stiffener tube when the stiffener tube is being compressed during a dispense cycle and the contents are free to flow through the openings or cutouts into the area between the inner stiffener tube and the outer soft metal tube. As the inner tube thereafter is allowed to return to its normal shape, that material can either become trapped between the stiffener tube and the soft metal tube or can flow back through the opening at a rate which may adversely impact the drawback or sniff back capability.
It would therefore be an improvement in the field of such soft metal crimp tube containers to provide a squeeze resistant stiffener which did not have the disadvantages described.